$OpenBSD: patch-src_ptlib_unix_tlibthrd_cxx,v 1.1 2017/05/07 20:48:29 espie Exp $
--- src/ptlib/unix/tlibthrd.cxx.orig	Fri Apr 28 01:44:49 2017
+++ src/ptlib/unix/tlibthrd.cxx	Fri Apr 28 01:44:58 2017
@@ -37,6 +37,7 @@
 #include <sched.h>
 #include <pthread.h>
 #include <sys/resource.h>
+#include <unistd.h>
 
 #ifdef P_RTEMS
 #define SUSPEND_SIG SIGALRM
